Solid state ignition system

ABSTRACT

A solid state ignition system is constructed for use with the flywheel magneto of either single or multiple cylinder engines and the ignition system utilizes a capacitor discharge ignition circuit arrangement. High energy pulses are produced by a permanent magnet on a flywheel rotating past a charge-trigger coil assembly which induces magnetic flux therein to generate and store energy in the capacitor of the ignition circuit. The charge-trigger coil assembly is a single constructed unit having both a capacitor charging coil and a trigger coil formed on a single paramagnetic core. Ignition timing advance is accomplished simultaneously with and as a result of increased engine speed. This automatic timing advance is accomplished by utilizing the uniform change in rise time of the first peak of a trinary peaked pulse waveform that is generated by the trigger winding. This first peak trigger pulse is used to discharge the capacitor after it has been charged by a previous trinary peaked waveform. The peak following the charge peak is blanked so that the first peak of the next waveform is used as the trigger pulse.

nited States Patent Beak et al. [4 June 13, 1972 SOLID STATE IGNITIONSYSTEM Primary Examiner-Martin P. Schwadron As'ttE 'CrtFl't [72]Inventors: Ljubomir Beuk; Peter Dogadko, both of fgsg, figgg i gChicago; Larry Sansbury, Elmhurst, all of 57 ABSTRACT [73] Asslgnee:Motorola Franklm Park A solid state ignition system is constructed foruse with the [22] Filed: Sept. 30, 1970 flywheel magneto of eithersingle or multiple cylinder engines and the ignition system utilizes acapacitor discharge ignition [2H Appl circuit arrangement. High energypulses are produced by a permanent magnet on a flywheel rotating past acharge-trigger [52] [1.8. CI. 1 23/148 E. 123/149 R, 123/1491 coilassembly which induces magnetic flux therein to generate I51 1 Int. Cl..F02p 3/06 and store energy in the capacitor of the ignition circuit.The [58] Field of Search 1 23/ l 49, 148; 315/2 09 T, 209 CD,charge-trigger coil assembly is a single constructed unit having 315/209SC, 218, 226 both a capacitor charging coil and a trigger coil formed ona 1 single paramagnetic core. ignition timing advance is accom-References Cited lished simultaneously with and as a result of increasedengine p d Th (1 1 h d b spee is automatic timing a vance is accomp is ey UNITED STATES PATENTS I utilizing the uniform change in rise time ofthe first peak of a 3,553,529 1/1971 Strelow "123/148 E trinary peakedpulse Waveform that is generated by the trigger 1,279,750 9/1918 Oglesby..123/ 149 F winding. This first peak trigger pulse is used to dischargethe 1,181,996 5/1916 Cunningham .....123/l49 F capacitor after it hasbeen charged by a previous trinary 3,398,353 8/1968 Noddin et a].....3l5/2l8X peaked waveform. The peak following the charge peak is3,405,347 10/1968 Swift et 1 ..l23/ 148 E blanked so that the first peakof the next waveform is used as the trigger pulse.

9 Claims, 5 Drawing Figures V I2 7 N f l6 I? m I I r" t C P ATENTEBJUN 13 m2 FIGZ 95c FIG5 INVENTORS. LJUBOMIR BEUK TSDNIS Hui H65 PETER DOGADKOLARRY SANSBURY BY WM ATTORNEYS.

SOLID STATE IGNITION SYSTEM BACKGROUND OF THE INVENTION This inventionrelates generally to an ignition system and more particularly to a solidstate capacitor discharge ignition system for operation with a flywheelmagneto of either single or multiple cylinder engines.

Heretofore, magneto type ignition systems found relative widespreaduse'with small gasoline engines, such as one, two, three or fourcylinder, two or four cycle engines, because this type of .ignitionsystem is relatively simple in circuit arrangement and componentrequirements and is inexpensive to produce while being easy to operate.Some of the magneto ignition systems of this type may include a flywheelmounted on the engine shaft and a permanent magnet, formed on or securedto the periphery of the flywheel. The permanent magnet is positioned ata particular location on the circumference of the flywheel with respectto the piston firing position of the engine. A paramagnetic core ismounted to a support on the engine so as to be firmly held in place andspaced in close proximity with the flywheel such that each time themagnet on the circumference of the flywheel passes the paramagneticcore, a magnetic field is induced into the core. This magnetic field isthus utilized to induce a voltage into' a winding on the paramagneticcore in a well-known manner. The voltage induced into the winding, as aresult of rotational movement of the magnet past the paramagnetic core,is applied through a diode and stored in a capacitor for a briefinterval before this energy is then applied to the primary winding of anignition coil by the closing of a breaker point assembly. That is, afterthe energy developed by the magnet and coil is stored in the capacitor,breaker points close abruptly to discharge the capacitor intothe'prirnary winding of a high voltage step-up ignition coil to inducesparkvoltage at its secondary winding. Although'these types of magnetoignition systems have proven relatively reliable and inexpensive for thegeneral purpose intended, i.e., providing ignition sparks for smallengines, they still have several problems which cause starting andrunning difficulty. Another, more conventional type of magneto ignition,is one where the breaker points are connected in shunt with coil windingand are closed during buildupof the magnet flux. The points are thenopened when maximum energy is stored in the winding to produce thenecessary spark discharge.

Among several of the problems of concern in such magneto ignitionsystems, one is the unreliability of components such as the breakerpoints. For example, at fast engine speed, even for small engines havinga few number of cylinders, there may be bounce of the breakerpoints'thus causing erratic ignition characteristics and poor engineoperation. In some cases the bounce will tend to discharge the capacitorof the ignition system prematurely so that when a subsequent operationof the breaker points occur, this now being at the proper ignitiontiming point, the reduced charge on the capacitor may be insufficient toeffect a proper ignition spark. Also, the rubbing block of the breakerpoints, which is of insulative material, tends to wear down with use,which is a common and unavoidable problem, and because of this, thebreaker points need adjustment from time to time, and eventuallyreplacement of the complete breaker point assembly is necessary. Pittingof the metal contacts of the breaker point assembly is also of concernin that the spacing of the gap between the contacts changes as a resultof such pitting and the ignition timing may be changed as a resultsufficient to cause hard starting or rough running. Also, this pitting,in many cases, will cause an increase in resistance between the metalcontacts to reduce the current flow therethrough and reduce the sparkenergy. Still another difficulty with regard to the breaker points, thisbeing particularly true with respect to small engines of the outdoorindustrial or recreational type, is that oil, gasoline, and dirt can geton the breaker points to cause a malfunction because of the highresistance when the points are closed, and in some cases, the breakerpoints will not make contact at all.

Another of the problems of such magneto ignition systems is theinability to produce a sufficiently high spark voltage over the completeoperating range of the engine, starting from low cranking speeds and allthe way up to the higher operating speeds. To insure sufficient highvoltage at the low cranking speed, a large number of turns are providedon a pickup coil positioned to receive magnetic flux from the magnet onthe flywheel, the amount of voltage being proportional to the number ofturns of the coil. High voltage can also be obtained by maximum magneticcoupling between the magnet on the flywheel and the pickup coil, thisbeing obtained by a close spacing, on the order of thousand of an inchbetween the pickup coil and the flywheel. However, at high engine speedseach of the above approaches to produce high voltage at low speedbecomes a problem at the higher speeds because too much voltage isobtained and may cause voltage breakdown and deterioration of thevarious components in the ignition system. Of particular concern is theincreased rate of deterioration of the spark plug electrodes at thehigher voltages particularly since this higher voltage is, in manycases, well in excess of that necessary to ensure proper ignition andcombustion of the fuel within-the engine.

Yet another of the problems of magneto ignition systems is their generalinability and/or complexity to provide gradual spark advance of theignition timing. Such magneto ignition systems, particularly for smallengines, either provide no spark advance whatever or provide only a stepfunction spark advance whatever to have one position for starting of theengine and a second position for optimum fast running speed of theengine. When no spark advance at all in incorporated, the ignitiontiming is generally set to afford the best possible startingcharacteristics while having a relatively efficient runningcharacteristic. However, this is true only for particular environmentalsituations such as temperature and humidity and because of changes ineither of these environmental conditions, the starting of the engine maybe very difficult, if not impossible. On the other hand, the stepfunction spark advance provides optimum conditions only for starting andmaximum running speeds and, as such, does not take into considerationthat the engine may at times be operated at intermediate speeds. Theintermediate speeds, therefore, depending on the point the step functionof spark advance occurs, either have no ignition advance or maximumignition advance and in either case it would be an improper timingcharacteristic for the intermediate engine speed and load than takingplace. This arrangement not only causes inefficient running of theengine, but wastes fuel and may cause substantial amounts of pollutantsin the form of unburnt gasoline to be exhausted into the atmosphere. I

Still another problem which arises with magneto ignition systems iswhere the pickup coil is a combined unit having both the chargingwinding and the trigger winding formed on a single paramagnetic core.This type of pickup coil has the advantage of being relativelyinexpensive and small in size. However, it produces a trinary peakedwaveform each time the flywheel magnet passes it. This trinary peakedwaveform has the disadvantage of providing a trigger pulse following thecharge pulse which does not have a gradually changing slope at theleading edge of the pulse. The slope of the trigger pulse, which followsthe charge pulse, changes erratically during changes in engine speed sothat any attempt to utilize this pulse to acquire a uniformly changingspark advance is futile. This subsequent pulse will, however, provide asatisfactory step function spark advance of ignition timing between slowspeed, i.e., cranking speed for starting, and high speed for doing work.Heretofore, the first peak of the trinary peaked waveform has not beenused as a trigger pulse because to do so would appear to discharge theignition capacitor before it is actually charged because the charging ofthe capacitor takes place after the first peak, i.e., during the secondpeak.

SUMMARY OF THE INVENTION Accordingly, the general objects of thisinvention are to provide an improved magneto type ignition system foruse with internal combustion engines.

The general objects of this invention include providing a magnetoignition system which requires no breaker point maintenance oradjustment and which completely eliminates ignition failure due tobreaker point malfunction.

Still among the general objects of this invention is the provision of amagneto type ignition system which produces a substantially uniformspark discharge over the entire operating range of engine speeds, fromcranking speed to full running speed, so that erosion of the spark plugelectrodes is maintained at a minimum.

The general objects further include providing a magneto type ignitionsystem which can provide a gradual spark advance of ignition timing overthe entire speed range of the engine from cranking speed, for easierstarting, to full running speed, for maximum efficiency.

One of the features of this invention is the utilization of a singlepickup coil structure which has a pair of windings formed about a commonparamagnetic core member. One winding is used to induce a large voltageinto a capacitor of a capacitor discharge ignition circuit and the otherwinding is used as a trigger pulse producing element, which eliminatesthe need of breaker points, to render a silicon controlled rectifierconductive and discharge the charged capacitor into the primary windingof an ignition coil. The charge delivered to the ignition coil istransformer coupled to a high voltage secondary winding which isconnected to the spark plug, thus producing the spark at its electrodes.

Yet another feature of this invention is the use of a blanking circuitwhich eliminates the trigger peak immediately following a charge peak sothat a first peak of a trinary peaked waveform can be used as thetrigger pulse. The trigger winding will develop three peaks, onepositive, the next negative and the last positive, again, while thecharge winding will have similar peaks, but of opposite polarity. Themiddle peak from the charge winding is applied to the capacitor of theignition circuit. However, because of the erratic change in rise time ofthe following third peak, this being due to the second peak also havingsome effects on the discharge of the capacitor, it is uniquely providedthat the first of the three peaks be used for triggering the ignitioncircuit while the third of such peaks is rendered ineffective in thecircuit. By utilizing the first of the three peaks, automatic andgradual spark advance of ignition timing is achieved as a result of thesmooth change in slope or rise time of the first peak. In the case ofafour cylinder engine, where two cylinders are fired simultaneously, thecoil pickups are mounted in pairs adjacent opposite sides of theflywheel and the charge winding of one coil pickup is associated withthe trigger winding of the other coil pickup and this crisscrossassociation provides trigger pulses which are the first pulses of thetrinary peaked waveform rather than the third pulses as is usually thecase. Where a single coil pickup is used, the third peak of each trinarypeaked waveform is eliminated by a special blanking circuit.

Briefly, the magneto ignition system of this invention includes aflywheel mounted permanent magnet, a chargetrigger coil structuremounted close to the magnet for producing both a capacitor chargingvoltage and a trigger voltage, an energy storage capacitor, a siliconcontrolled rectifier for discharging of the storage capacitor and a highvoltage ignition coil. The ignition coil may be of the type associatedwith each spark plug as is common for small gasoline engines. As themagnet mounted on the flywheel moves past the chargetrigger coilcombination, a high energy pulse is produced in the charge winding whilea lower energy trigger pulse is produced in the trigger winding. Wherethe ignition arrangement includes two such charge-trigger coilcombinations, each charge-trigger coil can be used to deliver sparks totwo cylinders simultaneously of a four cylinder, two cycle, engine. In

Iran:

this case only one of these sparks is effective because the othercylinder is on its exhaust stroke. The charge-trigger coil units are inopposite sides of the magneto flywheel alternately to develop a trinarypeaked waveform by the magnetic flux induced therein. High energy pulsesare retained in the storage capacitor until the trigger pulse from theopposite chargetrigger coil unit renders the associated siliconcontrolled rectifier conductive. This duplex arrangement of componentsprovides means to eliminate the effectiveness of the third peak of thepulse so that only the first peak is used as a trigger pulse.

In the case of a single cylinder engine, triggering is obtained from thesame type of charge-trigger coil combination, but in this case ablanking circuit is utilized to eliminate the third peak of the waveformto disable the ignition system for a short period of time during theexistence of this third peak. Therefore, during the following trinarypeaked waveform, the first peak is used as the trigger pulse to effect adischarge of the capacitor ignition system to produce a spark.

Initial timing of the magneto ignition system of this invention isobtained by precisely setting the magnet flywheel rela tive to thekeyway on the engine shaft so that this permits the charge on thecapacitor to occur substantially before top dead center of piston traveland fire the spark plug at the top dead center position at crankingand/or at slow speeds. Gradual spark advance of the ignition timing isobtained from the changing slope of the first peak trigger pulse whichchanges automatically with increasing engine speed, thus providing acompletely electronic spark advance system responsive only to enginespeed. This type of spark advance provides much smoother idling and easystarting of the engine as well as maximum power efficiency and fuelconsumption at the higher operating speeds. By the time the enginereaches its working speed, most of the ignition advance will haveoccured and the ignition advance will level off at the desired enginespeed. The solid state ignition system incorporated herein can be rathereasily modified and adapted to most single and multiple cylinderflywheel magneto type engines.

Along with basic design simplicity and elimination of breaker points,the magneto type ignition system of this invention also has severalperformance advantages over previous systems. Ignition coils can be usedwhich provide very fast high voltage rise time and a short sparkduration of approximately 75 microseconds to afford a better firing offouled spark plugs and extend their usable life considerably withoutadversely affecting engine performance. The combination of thecharge-trigger coil in one unit provides gradual spark advance ofignition timing, this advance occurring over a range of approximately24, more or less, and the maximum limit of spark advance can be set by asimple adjustment to conform to the particular type of engine involved.

A voltage dependent resistor is provided in the circuit to minimize theadverse effects of excessively high voltage sparks at high engine speed,a condition which would otherwise cause rapid deterioration of the sparkplug electrodes. That is, during high engine speed the high voltagecharge from the chargetrigger coil is somewhat limited by a voltagedependent resistor connected in parallel with the charge winding.Temperature compensation components are also provided in the circuit tostabilize the electronic advance characteristic and to provide for easystarting at temperature extremes. The circuit is simple and inexpensiveto manufacture and is efficient and reliable in operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of onecircuit arrangement of a magneto ignition system constructed inaccordance with this invention;

FIG. 2 is a schematic diagram of an alternate circuit arrangement of amagneto ignition system constructed in accordance with this invention;

FIG. 3 illustrates a trinary peaked waveform produced by the chargewinding of the pickup coil used in the circuit arrangement of thisinvention and which waveform is illustrative of slow engine speed;

FIG. 4 illustrates a trinary peaked waveform produced by the triggerwinding of the pickup coil used in this invention; and

FIG. 5 is a trinary peaked waveform similar to that of FIG. 4, but whichis illustrative of fast engine speed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, amagneto type solid state ignition system is designated generally byreference numeral and includes a plurality of ignition coilscorresponding in number to the number of cylinders associated with theengine, not shown, to which the ignition system may be incorporated.Here, a pair of ignition coils 12and 14 are connected in series, onewith the other, to receive the same current pulse and produce asimultaneous spark discharge at associated spark plugs 13 and 15,respectively. In'this arrangement the engine will have two of itspistons in the same position with'respect to top dead center, but eachwill be of a different stroke, i.e., one piston being in the powerstroke and the other piston being in the exhaust stroke. Spark dischargeat one of the spark plugs 13 or 15 during the exhaust stroke will haveno effect whatever on engine performance andonly the spark occurring inthe cylinder having the power stroke will ignite the fuel in thatparticular cylinder. Similarly, a second pair of ignition coils 16 and18 are connected in series, one with the other, and also includeassociated spark plugs 17 and 19, respectively. The ignition coils l6and 18, together with their spark plugs 17 and 19, are cooperative withanother pair of pistons of the engine in the same manner as mentionedabove.

Energizing current for the ignition coils 12, 14, 16 and 18 is providedby discharge of a capacitor at the proper time sequence during rotationof the engine. A capacitor 20 has one end thereof connected to groundpotential and its other end connected to the anode of an electronicswitch device 21, preferably it being a silicon controlled rectifier asillustrated herein. The cathode of the silicon controlled rectifier 21is connected to the positive terminal of the first ignition coil 12.Similarly, a second capacitor 22 has one end thereof connected to groundpotential and the other .end thereof connected'to the anode of a secondelectronic switch device 23, it also being a silicon controlledrectifier which, in turn, has its cathode connected to the positiveterminal of the ignition coil 16. Silicon controlled rectifiers 21 and23 are alternately rendered conductive so as to deliver energizingcurrent first to one pair of serially connected ignition coils and thento the other pair of ignition coils such that for each half cycle orhalf revolution of the engine a spark producing voltage is developed atthe appropriate one of the spark plugs 13, 15, 17 and 19.

First and second pickup coil means 26 and 27 are positioned in closespaced relation to a magneto flywheel 28 which is rotated by the crankshaft of the engine as is well-known in the art. The magneto flywheel 28has a permanent magnet segment 29 formed on or attached to thecircumference of the flywheel and is so positioned relative to a keyway30 so that proper timing of the engine is achieved.

The pickup coil means 26 has a paramagnetic core 31 about which is wounda pair of windings 32 and 33; the winding 32 being a capacitor chargingwinding and the winding 33 being a trigger circuit winding. A firstcircuit means is used to charge the capacitor 22 and is here shown asthe winding 32 which has one end thereof connected to ground potentialby a line 34 and the other end thereof connected to capacitor 22 througha diode 36. In this manner a relatively high voltage charge can beplaced on the capacitor 22, and diode 36 prevents the voltage fromleaking off because it is now reversed biased by the charge'on thecapacitor. The amount of voltage applied to capacitor 22 issubstantially limited, at least at high engine rpms, by a voltagedependent resistor 37 which is connected in shunt relation to thecharging winding 32. The rate at which the magnet 29 passes the windings32 and 33 will be one of the factors determining the voltage oncapacitor 22, Le, the faster the magnet moves, the higher the voltage.The voltage dependent resistor 37 therefore limits the amount of chargethat can be placed on the capacitor 22 during high speed operation, thusreducing the tendency of erosion of the spark plug electrodes as aresult of an over voltage condition.

A second circuit means, comprising lines 38 and 39, apply trigger pulsesfrom the trigger winding 32 to the gate cathode circuit of siliconcontrolled rectifier 21, thus causing conduction thereof to dischargethe associated capacitor 20. The gate-cathode circuit of siliconcontrolled rectifier 21 includes a variable resistance element 40, whichis used to set the upper limit of the automatic spark advance of theignition system, and a temperature responsive resistor 41, which is usedto stabilize the circuit under a wide range of temperature conditions toensure easy starting of the engine under all weather conditions.

The pickup coil means 27, in like manner, includes a capacitor chargingwinding 43 and a trigger winding 44. Here, the first circuit meansincludes a line 46 andadiode 47 connected in series with the capacitor20 to apply thereto a relatively high voltage charge, the value of whichis limited at high speeds by a voltage dependent resistor 48 connectedin parallel with the winding 43. A second circuit means includes a pairof lines 49 and 50 connected to the gate-cathode circuit of siliconcontrolled rectifier 23 to render the same conductive during theappropriate point in the ignition timing cycle. Here also a variableresistance element 51 is connected in parallel with a temperatureresponsive resistor 52 and each function substantially in the samemanner as do the variable resistance element 40 and the temperatureresponsive resistor 41. The crisscross or duplex interrelationshipbetween the charging capacitors 20 and 22, relative to the triggerwindings 32 and 44, respectively, provide a means for charging thecapacitors during the positive peak 75b of the waveform 75, FIG. 3,produced, and the charging windings 32 and 43 of the pickup coils 26 and27, respectively, while discharge of the capacitors occur at a point intime before it would otherwise be charged by the first peak 76a of thewaveform 76 of FIG. 4. The crisscrossing or duplex relationship of thetwo circuits is one means of rendering the third peak 750 or 766 of thetrinary peaked waveform ineffective in the circuit. Therefore, the firstpeak 760 of the next following trinary waveform produced at the triggerwinding is the one that is effective to trigger the silicon controlledrectifier associated therewith. That is, the third peak of the trinarypeaked waveform produced by each of the coil structures 26 and 27 willoccur at the gate of the associated silicon controlled rectifier when nocharge is on the associated capacitor in circuit therewith, and thefirst peak of the trinary peaked waveform will occur at the gate of thesilicon controlled rectifiers when a charge exists on the capacitors andwhich charge is the result of the second peak of a previous trinarypeaked waveform.

Referring now to FIG. 2, there is seen an alternate form of ignitionsystem which can be used with a magneto flywheel of an engine and isdesignated generally by reference numeral 60. Here, an ignition coil 61has the primary winding 62 thereof connected in parallel with a storagecapacitor 63 which supplies energizing current thereto to produce a highvoltage spark at a secondary winding 64. Connected in series with theprimary winding 62 is an electronic switching device 66, such as asilicon controlled rectifier, which is rendered conductive to dischargecapacitor 63 through the primary winding 62. A resistance element 67 anda diode 68 are connected in parallel with the primary winding 62 toprevent extraneous oscillations from occurring during rapid discharge ofcapacitor 63.

Pickup coil means 70 is provided with a capacitor charging winding 71and a trigger winding 72, and may take a form similar to either of thepickup coil means 26 or 27 of FIG. 1. However, in this embodiment,windings 71 and 72 are tied together at a common third circuit line 73,which, during normal running operation, is an ungrounded common line.

The pickup coil means 70 produces trinary peaked pulse waveforms in thesame manner as the pickups 26 and 27 of FIG. 1. The positive polarityportions 75b of waveform 75 is developed at the winding 71 and used tocharge the capacitor 63 and positive polarity portions 76a of thewaveform 76 from the winding 72 are used to trigger the siliconcontrolled rectifier 66. For example, the waveforms 75 and 76 of FIGS. 3and 4, respectively, illustrate the trinary peaked portions 75a, 75b and75c, and 76a, 76b and 76c, which is repetitive for each spark producedby the circuit 60. Also, the waveform 75 is that which is developedacross the winding 71 while the waveform 76 is developed across thewinding 72 is of the same wave configuration. but of opposite polarity.FIGS. 3 and 4 illustrate the trinary peaked waveform as produced at slowengine speeds when the magnet on the flywheel passes the pickup coilmeans 70 at a relatively slow speed. By way of example, the negativepeak 75a, as developed across the winding 71, has no effect on thecharging circuit of capacitor 63 because of the polarity of a seriesconnected diode 76. On the other hand, the positive second peak 75b isapplied through the diode 76 to charge capacitor 63. The maximum valueof this peak voltage is limited by a voltage dependent resistor 77connected in parallel with the winding 71, this limiting actionoccurring most effectively at the higher engine speeds. Now thatcapacitor 63 is charged, a trigger pulse applied to silicon controlledrectifier 66 will discharge the capacitor and produce a spark. However,the subsequent peak 760, which is positive from winding 72, is notsensed at the gate-cathode circuit of silicon controlled rectifier 66because this pulse is blanked by placing a charge across a capacitor 78during the same time the capacitor 63 is charged. The blanking charge oncapacitor 78 is applied through a diode 79, a resistor 80 and a seconddiode 81. Resistor 80 forms part of a voltage divider network with asecond resistor 82 to limit the voltage value on capacitor 78. Theblanking charge on capacitor 78 will render a second silicon controlledrectifier 83 highly conductive and this second silicon controlledrectifier is connected across the gate-cathode circuit of the mainsilicon controlled rectifier 66. That is, capacitor 78 is connected tothe gate-cathode circuit of silicon controlled rectifier 83 through aresistor 84 which holds this silicon controlled rectifier in a highlyconductive state. The low resistance current path produced as a resultof the high conductive state of silicon controlled rectifier 83 willnullify any signal by substantially short circuiting the gatecathodevoltage on the main silicon controlled rectifier 66 thereby causing thethird peak 760 to be ineffective. Capacitor 78 will continue todischarge through resistor 84 and the gatecathode circuit of the siliconcontrolled rectifier 83 for the entire duration ofthe peak 76c.

A transistor 86 has its emitter-collector junction connected in parallelwith the capacitor 78 and is rendered conductive by the first peak 760to ensure complete discharge of capacitor 78 or at least to a sufficientlevel so that the silicon controlled rectifier 83 is renderednon-conductive when the first peak 76a again occurs. It is this firstpeak 76a that renders silicon controlled rectifier 66 conductive todischarge capacitor 63 and produce a spark at the secondary winding 64of the ignition coil 61. The base electrode of the transistor 86 isconnected to the trigger winding 72 via a resistor 87 which applies thenecessary bias to the transistor 22. The trigger winding 72 is connectedto the gate electrode of silicon controlled rectifier 66 through aresistor 88 and a diode 89 connected in series therewith.

To insure proper operation of the silicon controlled rectifier 66, afixed resistor 90 and a variable resistor 91 are connected in agate-cathode circuit thereof together with a temperature responsiveresistor 92, which is used to stabilize the circuit. However, fixedresistor 90 may be eliminated if desired. Variable resistor 91 is usedto set the maximum degree of advance of the spark discharge for theparticular engine involved. That is, the total number of degrees ofspark advance can be adjusted for each different kind of engine usingthe ignition system of this invention merely by adjusting the value ofthe resistor 90 which changes the voltage level on the gatecathodecircuit. To prevent extraneous firing of silicon rectifier 66, acapacitor 93 is provided to shunt any transient voltages which may occurin the gate-cathode circuit thereof.

A Run-Stop switch 94 is provided and has the movable contact thereofconnected to ground potential and which is switched between an opencircuit condition and a closed circuit connection which will connectground to the common line 73. When the common line 73 is grounded inthis manner, a high energy pulse that may be applied to storagecapacitor 63 is effectively shunted to ground, and no output sparkvoltage will be developed.

Referring now to FIG. 5, the trinary peaked waveform is designatedgenerally by reference. numeral 95 and has the first peak designated byreference numeral 95a, the second peak by reference numeral 95b, and thethird peak by reference numeral 95c, and this waveform is representativeof fast engine speed as compared to trinary peaked waveform 75 and 76,shown in the FIGS. 3 and 4, for slow engine speed. The wavefonn of FIG.5 illustrates what takes effect at the higher engine speeds. Here, itcan be seen that by utilizing the first peak 76a of FIG. 4, or 95a ofFIG. 5, the rate of change of slope of the leading edge of this peakchanges gradually and uniformly to provide an automatic and gradualspark advance of ignition timing over the entire speed range of theengine. At lower speeds, the slope of the leading edge of the peak 76awill produce a spark at point 99 which will be near top dead center ofthe piston while at higher speeds the rapid increase in slope of theleading edge, as shown by the peak 95a, will cause the spark to occur atpoint 100 which is as much as 35, more or less, before top dead centerof the piston.

The reason that peak 760 cannot be used to provide uniform gradual sparkadvance is that it follows the charging peak 75b and the slope betweenthe peaks 76b and 760 does not change gradually with gradual increasesof engine speed. The charging peak 75b is seen as a gradual change froma maximum positive voltage to a maximum negative voltage. However, atthe higher speed this change occurs abruptly from a positive voltage tonegative voltage to produce the third peaked pulse 95c with almost avertical slope at the leading edge of the waveform 950, as seen in FIG.5. It is this third peak 750 or 95c which is blanked or eliminated bythe blanking circuit of FIG. 2 so that the first peak 75a or 95a servesas the trigger pulse.

What has been described is a highly efficient circuit arrangementwhereby a trinary peaked waveform is developed and only the first peak,one that precedes a charging peak, is used as a trigger pulse for theignition circuit. This first peak, therefore, provides uniform gradualsparked advance of ignition timing throughout the entire range of enginespeeds because of the uniform gradual change in slope of the leadingedge of this peak. Accordingly, it will be understood that thevariations and modifications of this invention may be effected withoutdeparting from the spirit and scope of the novel concepts disclosed andclaimed herein.

We claim:

1. In an ignition system including in combination,

an ignition coil means having a primary winding for receiving a currentpulse and a secondary winding for generating high voltage sparkdischarges;

capacitor means connected to the primary winding of the ignition coilmeans;

electronic switch means connected in series with said primary windingselectively being rendered conductive to discharge the capacitor meanstherethrough and to produce a current pulse in the primary winding; thecombination including:

pickup coil means including first and second coils positioned adjacent arotating magnet for producing a trinary peaked waveform in each of saidcoils responsive to each revolution of said magnet;

first circuit means for applying a peak of each of the trin ary peakedwaveforms produced in said first coil upon each revolution of saidmagnet to said capacitor means to charge the same; and

second circuit means for applying a peak of each of said trinary peakedwaveforms produced in said second coil upon each revolution of saidmagnet to said electronic switch means to render the 7 same conductiveand discharge the capacitor means into said primary winding of theignition coil means to cause a spark; and

third circuit means for eliminating the effectiveness of one peak ofeach of said trinary peaked waveforms produced by said second coil toprevent discharge of the capacitor means more than once during onecomplete cycle of said trinary peaked waveform produced by said secondcoiland to provide for ignition advance.

2. The ignition system of claim 1 wherein said pickup coil meansincludes two sets of first and second coils each set being positioned ondiametrically opposed sides of a magneto flywheel associated with theengine utilizing said ignition system, and whereinsaid capacitor meansand said electronic switch means include one capacitor and oneelectronic switch operatively associated with each set of first andsecond coils.

3. The ignition system of claim 1 further including voltage limitingmeans connected in circuit with said capacitor means to limit thevoltage charge on said capacitor means at high engine speeds.

4. The ignition system of'claim 1 wherein said electronic switch meanscomprises a silicon controlled rectifier having the gate-cathode circuitthereof arranged for receiving said first peak of said trinary peakedwaveform from said second coil and further including a variableresistance element connected in the gate-cathode circuit to adjust themaximum amount of ignition timing advance to be obtained.

5. The ignition system of claim 1 wherein said third circuit meansincludes second capacitor means connected in circuit with said firstcoil of said pickup coil means to be charged in response to the secondpeak of said trinary peaked waveform generated therein;

a silicon controlled rectifier having the anode-cathode circuit thereofconnected across said electronic switch means to disable the same whensaid silicon controlled rectifier is in the conductive state, the gateelectrode of said silicon controlled rectifier being connected to saidsecond capacitor and rendered conductive in response to the charge onsaid second capacitor; and

a current control device having control and load electrodes with itsload electrodes connected across said second capacitor and its controlelectrode connected in circuit with said second coil of said pickup coilmeans to be rendered conductive to discharge said capacitor during saidfirst peak of said trinary peaked waveform in said second coil so thatsaid first peak will also render said electronic switch means conductiveto produce a spark at said ignition coil.

6. An ignition system comprising, in combination:

a pickup coil to be positioned adjacent a rotating magnet on an engine,said pickup coil including a'charging winding and a trigger winding on acommon paramagnetic core, said pickup coil producing a trinary peakedwaveform in each of said windings with the second peak within saidcharging winding being the charging voltage and the first peak in thetrigger winding being used as the trigger voltage;

a storage capacitor connected in circuit with said charging winding toreceive charge therefrom as a result of said second peak; I

a main switching silicon controlled rectifier having its cathode-anodecircuit connected in series with said storage capacitor with itsgage-cathode circuit connected to said trigger winding;

terminal means connected to said silicon controlled rectifier fordirecting the discharge current from said storage capacitor through aprimary winding of an ignition coil;

a current control device connected in shunt relation to the gate-cathodecircuit of said silicon controlled rectifier to be highly conductiveduring the period of time corresponding to the third peak of said trmarypeaked waveform to prevent said silicon controlled rectifier from beingrendered conductive during this third peak;

a disabling capacitor connected between said charging winding and saidcurrent control device to receive charge as a result of said second peakof said trinary peaked waveform to render said current control devicehighly conductive during said third peak, said disabling capacitordischarging through a resistive path a portion of which includes saidcurrent control device and becoming substantially discharged prior tothe first peak of a subsequent trinary peaked waveform; and

a transistor having the emitter-collector electrode thereof connectedacross said disabling capacitor to completely discharge the same inresponse to said first peak of said trinary waveform from saidtriggering winding.

7. The ignition system of claim 6, wherein said current control deviceis a second silicon controlled rectifier having its anode-cathodeelectrodes connected to the gate-cathode electrodes of the mainswitching silicon controlled rectifier.

8. The ignition system of claim 6, further including a variableresistance element connected in the gate-cathode circuit of said mainswitching silicon controlled rectifier to vary the amount of sparkadvance of ignition timing.

9. The ignition system of claim 6, further including a voltage dependentresistor connected across said charging windin g to limit the voltagecharge on said storage capacitor during high engine speed.

1. In an ignition system including in combination, an ignition coilmeans having a primary winding for receiving a current pulse and asecondary winding for generating high voltage spark discharges;capacitor means connected to the primary winding of the ignition coilmeans; electronic switch means connected in series with said primarywinding selectively being rendered conductive to discharge the capacitormeans therethrough and to produce a current pulse in the primarywinding; the combination including: pickup coil means including firstand second coils positioned adjacent a rotating magnet for producing atrinary peaked waveform in each of said coils responsive to eachrevolution of said magnet; first circuit means for applying a peak ofeach of the trinary peaked waveforms produced in said first coil uponeach revolution of said magnet to said capacitor means to charge thesame; and second circuit means for applying a peak of each of saidtrinary peaked waveforms produced In said second coil upon eachrevolution of said magnet to said electronic switch means to render thesame conductive and discharge the capacitor means into said primarywinding of the ignition coil means to cause a spark; and third circuitmeans for eliminating the effectiveness of one peak of each of saidtrinary peaked waveforms produced by said second coil to preventdischarge of the capacitor means more than once during one completecycle of said trinary peaked waveform produced by said second coiland toprovide for ignition advance.
 2. The ignition system of claim 1 whereinsaid pickup coil means includes two sets of first and second coils eachset being positioned on diametrically opposed sides of a magnetoflywheel associated with the engine utilizing said ignition system, andwherein said capacitor means and said electronic switch means includeone capacitor and one electronic switch operatively associated with eachset of first and second coils.
 3. The ignition system of claim 1 furtherincluding voltage limiting means connected in circuit with saidcapacitor means to limit the voltage charge on said capacitor means athigh engine speeds.
 4. The ignition system of claim 1 wherein saidelectronic switch means comprises a silicon controlled rectifier havingthe gate-cathode circuit thereof arranged for receiving said first peakof said trinary peaked waveform from said second coil and furtherincluding a variable resistance element connected in the gate-cathodecircuit to adjust the maximum amount of ignition timing advance to beobtained.
 5. The ignition system of claim 1 wherein said third circuitmeans includes second capacitor means connected in circuit with saidfirst coil of said pickup coil means to be charged in response to thesecond peak of said trinary peaked waveform generated therein; a siliconcontrolled rectifier having the anode-cathode circuit thereof connectedacross said electronic switch means to disable the same when saidsilicon controlled rectifier is in the conductive state, the gateelectrode of said silicon controlled rectifier being connected to saidsecond capacitor and rendered conductive in response to the charge onsaid second capacitor; and a current control device having control andload electrodes with its load electrodes connected across said secondcapacitor and its control electrode connected in circuit with saidsecond coil of said pickup coil means to be rendered conductive todischarge said capacitor during said first peak of said trinary peakedwaveform in said second coil so that said first peak will also rendersaid electronic switch means conductive to produce a spark at saidignition coil.
 6. An ignition system comprising, in combination: apickup coil to be positioned adjacent a rotating magnet on an engine,said pickup coil including a charging winding and a trigger winding on acommon paramagnetic core, said pickup coil producing a trinary peakedwaveform in each of said windings with the second peak within saidcharging winding being the charging voltage and the first peak in thetrigger winding being used as the trigger voltage; a storage capacitorconnected in circuit with said charging winding to receive chargetherefrom as a result of said second peak; a main switching siliconcontrolled rectifier having its cathode-anode circuit connected inseries with said storage capacitor with its gage-cathode circuitconnected to said trigger winding; terminal means connected to saidsilicon controlled rectifier for directing the discharge current fromsaid storage capacitor through a primary winding of an ignition coil; acurrent control device connected in shunt relation to the gate-cathodecircuit of said silicon controlled rectifier to be highly conductiveduring the period of time corresponding to the third peak of saidtrinary peaked waveform to prevent said silicon controlled rectifierfrom being rendered conductive during this third peak; a disablingcapacitoR connected between said charging winding and said currentcontrol device to receive charge as a result of said second peak of saidtrinary peaked waveform to render said current control device highlyconductive during said third peak, said disabling capacitor dischargingthrough a resistive path a portion of which includes said currentcontrol device and becoming substantially discharged prior to the firstpeak of a subsequent trinary peaked waveform; and a transistor havingthe emitter-collector electrode thereof connected across said disablingcapacitor to completely discharge the same in response to said firstpeak of said trinary waveform from said triggering winding.
 7. Theignition system of claim 6, wherein said current control device is asecond silicon controlled rectifier having its anode-cathode electrodesconnected to the gate-cathode electrodes of the main switching siliconcontrolled rectifier.
 8. The ignition system of claim 6, furtherincluding a variable resistance element connected in the gate-cathodecircuit of said main switching silicon controlled rectifier to vary theamount of spark advance of ignition timing.
 9. The ignition system ofclaim 6, further including a voltage dependent resistor connected acrosssaid charging winding to limit the voltage charge on said storagecapacitor during high engine speed.